1. Field of the Invention
This invention relates to an automatic lubrication or oiling system for use with a power transmission chain and the like, and more particularly to an automatic lubrication system which is best suited for feeding a small amount of oil.
2. Brief Description of the Prior Art
It is well known that suitable lubrication is required for power transmission chains for use with a conveyor or an escalator, wire ropes such as cables, gears, and the surfaces of sliding motion such as machine tools hereinafter referred to as operating bodies for the purpose of preventing wear in such operating bodies.
To describe the situation in more detail, let us take a power transmission chain. The life of these chains depends on a wear of chain joints; thus, they should be protected against dirt and moisture which assists chain wear, and required suitable lubrication be applied to chain joints. On the other hand, the prior art low pressure automatic lubrication systems are generally classified into three types, one being a drip feed type in which lubricating oil is supplied intermittently in the form of droplets applied to points to be lubricated. Another type is an "oil-mist" or injection spray type system wherein the lubricating oil is sprayed or injected in the form of a mist on the points to be lubricated. The third type system is a so-called "continuous oil feeding" type in which lubricating oil is continuously fed in the form of a stream toward points to be lubricated. Any of these types of lubricating systems have inherent disadvantages and are not suitable as a lubricating apparatus for use in lubricating, for example, a power transmission train.
More particularly, the "drip-feed" type has a disadvantage that it is difficult to coincide with good timing the droplets discharged from a nozzle with the link points on the power transmission train so that a considerable variation in lubrication will occur at each link joint. The "oil-mist" or injection-spray type system has the disadvantage that, although no variation in lubrication at each link joint occurs, if used in a power chain transmission system, the lubricating oil is dispersed on areas other than the area to be lubricated, thereby contaminating the environmental surroundings.
Furthermore, the "continuous oil feeding" type lubricating system has the disadvantage that, since the discharge rate of the lubricating oil is relatively high, for example, more than 100 cc/min, excessive lubrication occurs so that almost all of the lubricating oil flows downwardly past the points to be lubricated, thereby contaminating the environmental surroundings in a manner similar to the "oil-mist" type lubrication system.
Additionally, in the "continuous oil feeding" type lubricating system, there are basically two types of systems, with the first being a system where the lubricating oil is continuously directed downwardly for a predetermined period of time to lubricate points to be lubricated, with the other type of system being constructed so that the lubricating oil is applied on the points to be lubricated at the proper time in response to a motion of the member to be lubricated. In these last-mentioned types of systems, excessive lubrication will nevertheless occur even if the lubricating oil is fed at a proper time to make short the period of time during which the lubrication is to be carried out, because the discharge rate of the lubricating oil from the nozzle is more than 100 cc/min. As a counter-measure to the excessive lubrication, it has been proposed to dispose an oil pan below the power transmission trains; however, such proposal is disadvantageous in that a space for such oil pan is required and, if there is no space available, it is not possible to dispose the oil pan below the power transmission chains. Additionally, by the provision of an oil pan, it would be necessary to take appropriate steps to provide for drainage of such oil pan, thereby requiring additional labor and maintenance expenses.
For these reasons, lubrication for operating bodies in general has been effected by a "brush" type lubrication by an operator. However, a disadvantage of such lubrication resides in the fact that considerable time and effort is involved in addition to exposing operators, to unnecessary dangers.